The present invention relates to grooves for chemical mechanical polishing pads. More particularly, the present invention relates to groove designs for increasing removal rate, improving global uniformity and reducing defects during chemical mechanical polishing.
In the fabrication of integrated circuits and other electronic devices, multiple layers of conducting, semiconducting and dielectric materials are deposited onto and removed from a surface of a semiconductor wafer. Thin layers of conducting, semiconducting and dielectric materials may be deposited using a number of deposition techniques. Common deposition techniques in modern wafer processing include physical vapor deposition (PVD), also known as sputtering, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD) and electrochemical plating, among others. Common removal techniques include wet and dry isotropic and anisotropic etching, among others.
As layers of materials are sequentially deposited and removed, the uppermost surface of the wafer becomes non-planar. Because subsequent semiconductor processing (e.g., metallization) requires the wafer to have a flat surface, the wafer needs to be planarized. Planarization is useful for removing undesired surface topography and surface defects, such as rough surfaces, agglomerated materials, crystal lattice damage, scratches and contaminated layers or materials.
Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize or polish work pieces such as semiconductor wafers. In conventional CMP, a wafer carrier, or polishing head, is mounted on a carrier assembly. The polishing head holds the wafer and positions the wafer in contact with a polishing layer of a polishing pad that is mounted on a table or platen within a CMP apparatus. The carrier assembly provides a controllable pressure between the wafer and polishing pad. Simultaneously, a polishing medium (e.g., slurry) is dispensed onto the polishing pad and is drawn into the gap between the wafer and polishing layer. The polishing pad and wafer typically rotate relative to one another to polish a substrate. As the polishing pad rotates beneath the wafer, the wafer sweeps out a typically annular polishing track, or polishing region, wherein the wafer's surface directly confronts the polishing layer. The wafer surface is polished and made planar by chemical and mechanical action of the polishing layer and polishing medium on the surface.
Reinhardt et al., U.S. Pat. No. 5,578,362 discloses the use of grooves to provide macrotexture to the pad. In particular, it discloses a variety of patterns, contours, grooves, spirals, radials, dots or other shapes. Specific examples included in Reinhardt are the concentric circular and the concentric circular superimposed with an X-Y groove. Because the concentric circular groove pattern provides no direct flow path to the edge of the pad, the concentric circular groove has proven the most popular groove pattern.
Lin et al., in U.S. Pat. No. 6,120,366, at FIG. 2, disclose a combination of circular plus radial feeder grooves. This example illustrates adding twenty-four radial feeder grooves to a concentric circular groove pattern. The disadvantage of this groove pattern is that it provides limited improvement in polishing with a substantial increase in slurry usage and shorter pad life due to less landing area on the polishing pad.
Notwithstanding, there is a continuing need for chemical mechanical polishing pads having better combination of polishing performance and slurry usage. Furthermore, there is a need for grooves that increase removal rate, lower slurry usage, improve global uniformity and reduce defects during chemical mechanical polishing.